Abstract
Dollar spot is caused by the fungus Clarireedia jacksonii and is the most common disease of golf course turfgrass in temperate climates. Oxalic acid (OA) is an important pathogenicity factor in other fungal plant pathogens, such as the dicot pathogen Sclerotinia sclerotiorum, but its role in C. jacksonii pathogenicity on monocot hosts remains unclear. Herein, we assess fungal growth, OA concentration, and pH change in potato dextrose broth (PDB) following incubation of C. jacksonii. In addition, OA production by C. jacksonii and S. sclerotiorum was compared in PDB amended with creeping bentgrass or common plant cell wall components (cellulose, lignin, pectin, or xylan). Our results show that OA production is highly dependent on the environmental pH, with twice as much OA produced at pH 7 than pH 4 and a corresponding decrease in PDB pH from 7 to 5 following 96 h of C. jacksonii incubation. In contrast, no OA was produced or changes in pH observed when C. jacksonii was incubated in PDB at a pH of 4. Interestingly, C. jacksonii increased OA production in response to PDB amended with creeping bentgrass tissue and the cell wall component xylan, a major component of grass cell walls. S. sclerotiorum produced large amounts of OA relative to C. jacksonii regardless of treatment, and no treatment increased OA production by this fungus, though pectin suppressed S. sclerotiorum’s OA production. These results suggest that OA production by C. jacksonii is reliant on host specific components within the infection court, as well as the ambient pH of the foliar environment during its pathogenic development.
Highlights
Dollar spot on cool-season turfgrass is caused by the fungus Clarireedia jacksonii and is the most economically important disease of golf course turfgrass in temperate climates (Vargas, 1994; Salgado-Salazar et al, 2018)
The results presented here indicate a strong association between ambient pH and Oxalic acid (OA) production in C. jacksonii and support earlier research from S. sclerotiorum and other plant pathogens that OA is used to alter ambient pH and create conditions conducive to infection
These data suggest that C. jacksonii prefers an acidic environment in vitro, which could indicate a similar preference in natural environments and during pathogenesis
Summary
Dollar spot on cool-season turfgrass is caused by the fungus Clarireedia jacksonii (formerly Sclerotinia homoeocarpa) and is the most economically important disease of golf course turfgrass in temperate climates (Vargas, 1994; Salgado-Salazar et al, 2018). Neutral pH Increases Oxalic Acid temperature range and relative lack of effective cultural practices for suppressing dollar spot have led to reliance on synthetic fungicides for disease suppression (Latin, 2011). Further support for the pH-altering properties of OA in S. sclerotiorum was provided by Xu et al (2015) They found that oxalate-minus mutants could not infect faba bean (Vicia faba), pea (Pisum sativum), green bean (Phaseolus vulgaris), and soybean (Glycine max) at a pH of 7 but could infect certain hosts when the pH was 4.2, suggesting that OA was not needed for pathogenesis when tissue pH was already low. The importance of OA in altering tissue pH to facilitate infection has been observed in the plant pathogen Botrytis cinerea, where Manteau et al (2003) found that OA was only produced in culture at a pH above 5. The majority of OA research in S. sclerotiorum and other pathogens suggests that OA is produced to decrease tissue pH and make conditions more favorable for pathogen infection (Xu et al, 2018)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
